Carrier Ring With Flexible Membrane for CMP Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current chemical mechanical polishing (CMP) technologies face challenges in maintaining consistent substrate loading and preventing torquing of the retaining ring during polishing, leading to uneven wear and process variability.
Innovation Solution
A carrier ring and retaining ring assembly with a flexible membrane and annular concentric recesses, where the flexible membrane is clamped to the carrier head and the retaining ring has a bonding layer and slurry transport channels, allowing independent load adjustment and reducing carrier distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional carrier head with retaining ring is used, then the substrate can be held in place during polishing, but torquing of the retaining ring occurs leading to uneven wear and process variability
Solution Approach 1:
The carrier head is divided into separate functional components: a carrier ring for applying downward pressure, a retaining ring for holding the substrate, and a flexible membrane for load transmission. This segmentation allows each component to perform its specific function independently, preventing torquing of the retaining ring while maintaining substrate holding stability.
Solution Approach 2:
A flexible membrane is introduced as an intermediary element between the carrier ring and the retaining ring. This membrane transmits load uniformly while accommodating dimensional differences and preventing direct mechanical coupling that would cause torquing. The membrane acts as a mediator that decouples the pressure application function from the substrate holding function.
2Device complexity
If the carrier ring directly contacts the retaining ring, then structural simplicity is maintained, but carrier distortion occurs and load consistency is compromised
Solution Approach 1:
A flexible membrane in the form of a thin film is introduced between the carrier ring and retaining ring. This flexible film accommodates dimensional differences between the two rings, transmits load uniformly across the interface, and prevents carrier distortion. The flexibility of the membrane allows it to conform to slight variations while maintaining consistent load transmission.
3Productivity
If higher polishing pressures are used, then polishing speed increases, but uneven wear of the retaining ring occurs reducing its lifespan
Solution Approach 1:
By separating the load application function (carrier ring) from the substrate holding function (retaining ring), the system allows the carrier ring to bear the full polishing pressure while the retaining ring maintains consistent, distributed contact with the substrate. This segmentation prevents concentration of wear on the retaining ring, extending its lifespan while maintaining high polishing speeds.
Solution Approach 2:
The flexible membrane serves as a load-distributing intermediary that prevents stress concentration on the retaining ring. It transmits pressure uniformly across the interface between the carrier ring and retaining ring, ensuring even wear distribution and extending the retaining ring's operational life while allowing high polishing pressures to be applied.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration ensures consistent substrate loading, reduces torquing of the retaining ring, and extends its lifespan by minimizing uneven wear and process variability, enabling lower polishing pressures and improved polishing uniformity.
Implementation Method 1
a flexible membrane shaped to provide an annular chamber positioned beneath the base assembly and above the annular retaining ring
Implementation Method 2
The annular upper portion and the annular lower portion of the retaining ring can be formed of different materials with a bonding layer between the two portions
Data Source
Figure 1
Figure 2A~2D
Figure 3A~3B
AI summary
A carrier head that has a base assembly, a retaining ring assembly, a carrier ring, and a flexible membrane is described. A carrier ring has an annular upper portion (431) and an annular lower portion (432) having a lower surface (433) with a smaller inner diameter than the upper surface of the annular upper portion, wherein the carrier ring circumferentially surrounds a retaining ring and has a lower surface to contact a polishing pad.